This invention relates in general to friction clutches and transmissions for vehicles and in particular to an improved structure for a clutch brake adapted for use with such clutches and transmissions.
In vehicular drive trains, it is well known to utilize a friction clutch to selectively disconnect an engine from a transmission in order to permit the transmission to perform a gear shifting operation. Prior to such a gear shifting operation, gears to be mated together within the transmission are driven by the engine at different rotational speeds. The clutch is disengaged so that the mating gears are not continued to be driven by the engine and, therefore, can be aligned with one another prior to the gear shifting operation. This pre-shifting alignment prevents undesirable clashing of the gear teeth. However, in a non-synchronized transmission, the rotating shaft which connects the clutch to the transmission continues to rotate for a period of time after the clutch has been disengaged because of momentum and clutch drag. Thus, in such non-synchronized transmissions, it is necessary to provide some means for slowing or stopping the rotation of this transmission input shaft when the clutch is disengaged to permit the alignment of the gears as described above.
The clutch brake is a device which is well known in the art for slowing or stopping the rotation of the transmission input shaft when the clutch is disengaged. Being generally flat and annular in shape, the clutch brake is disposed about the transmission input shaft between the rearward end of a release bearing for the clutch and the forward end of the transmission. Typically, the clutch brake is splined onto the transmission input shaft so as to rotate therewith, while being movable axially therealong. The release bearing is also mounted about the transmission input shaft for axial movement therealong.
Normally, the release bearing moves between engaged (near the clutch) and disengaged (near the transmission) positions for causing the clutch to selectively connect and disconnect the transmission input shaft from the engine. When so moved, the clutch brake is not engaged by the release bearing and, consequently rotates freely with the transmission input shaft. However, when it is desired to slow or stop the rotation of the transmission input shaft, the release bearing may be moved beyond the disengaged position further toward the transmission. When so moved, the clutch brake is frictionally engaged between the release bearing and the forward end of the transmission. As a result, rotation of the clutch brake, as well as of the transmission input shaft, is slowed or stopped.
Because they are relatively small in size, and further because they are frequently subjected to large torsional forces during use, clutch brakes generally have shorter service lives than the clutches or transmissions with which they are used. Thus, it is often necessary to replace a worn clutch brake without otherwise servicing the clutch or transmission. In the past, most clutch brakes have been formed as an annular metallic assembly. Because of its annular shape, such a prior clutch brake could be replaced only by partially disassembling the clutch or transmission so as to free one end of the shaft upon which the clutch brake was mounted, thereby allowing the clutch brake to slide off. More recently, clutch brakes have been formed from two mating halves secured about the shaft. Clutch brakes of this type can be removed and installed without partially disassembling the clutch or transmission. However, such clutch brakes have relatively complicated in structure and sometimes difficult to remove from the shaft.